The application of robotic devices and general-purpose transport platforms has enjoyed enormous growth in recent years, across all sectors of industrial, military and consumer/household operations, for a range of tasks limited only by the imagination of those employing such devices. These have included such disparate applications as surveillance, bomb disposal, industrial maintenance and household chores. In response to these demands, a number of configurations have been developed to provide enhanced-mobility vehicle structures that can be used in transport and robotic device applications over rough surfaces or terrain. Representative examples of such configurations are disclosed in the following U.S. Pat. Nos.:                6,144,180        5,833,248        5,742,975        5,579,857        5,515,934        5,507,358        5,323,867        4,993,912        4,932,491        
By way of example, U.S. Pat. No. 6,144,180 discloses a robot having a body, a pair of lift arms mounted pivotally on the body, a pair of leg support arms mounted pivotally on the lift arms, and a pair of wheeled leg assemblies mounted pivotally on each of the leg support arms. Each of the leg support arms is rotatable to turn one of the wheeled leg assemblies, which rests on the ground at the back of the other one of the wheeled leg assemblies, to a position in front of the other one of the wheeled leg assemblies, thereby moving forward the robot body. The lift arms can be rotated upward or downward relative to the leg support arms to lift or lower the robot body.
U.S. Pat. No. 5,833,248 purports to show a stairway ascending/descending vehicle that can ascend or descend stair-steps having a height greater than the diameter of the vehicle's wheels. The vehicle has mainshafts rotatably supported on a front portion and a rear portion of a vehicle body, respectively. Front arm members are mounted to the front mainshafts; rear arm members are mounted to the rear mainshaft; and the front and rear arm members are configured to rotate with respect to the mainshafts.
U.S. Pat. No. 5,742,975 discloses an articulated vehicle for scrubbing floor surfaces defined by intersecting aisles of relatively narrow width. The vehicle has articulated portions that facilitate turns in narrow aisles.
U.S. Pat. Nos. 5,579,857 and 5,507,358 disclose stair-climbing vehicles having a body, front and rear wheels provided at the front and rear of the vehicle body, respectively, front and rear auxiliary wheels for lifting the front and rear wheels, respectively, by one stair-step, a driving unit for driving each wheel, a pivoting unit for pivoting the front and rear auxiliary wheels, sensors for detecting a riser portion of stairs, and a control unit for controlling the driving unit and the rotating unit in accordance with outputs of the sensors. It is claimed that since the vehicle ascends/descends stairs by rotation of the auxiliary wheels, a corner portion of the step of stairs is not damaged while the vehicle goes up and down stairs.
U.S. Pat. No. 5,515,934 discloses a modular robot body assembly segmented into five modules, symmetrically located around a horizontal center shaft system, enabling the robot body, front legs, and back legs to rotate about a horizontal center axis with respect to one another.
U.S. Pat. No. 5,323,867 discloses a robot transport platform adapted for locomotion, having a base with three wheels on each side. The wheels near the fore and aft ends are omnidirectional in design, while the intermediate wheel (between the omnidirectional wheels) is a conventional wheel. The omnidirectional wheels have staggered rows of spherical rollers rotatably mounted to the circumference of the wheel's hub. Torque is provided by two electric motors independently operating the wheels on each side, and is transferred to the wheels via a gear box, a chain, and cogged drive belts.
U.S. Pat. No. 4,993,912 discloses a stair climbing robot having a chassis with powered, opposed front wheels and two pairs of rear wheels, each pair being rotatably mounted on a beam at opposite ends thereof, and each beam being rotatably mounted on the chassis. A drive motor is provided for driving each pair of wheels in the same direction at a predetermined rotational velocity; and a drive means is provided for simultaneously rotating the beams at a predetermined rotational velocity and in a predetermined direction. In operation, the beams rotate forward while each pair of rear wheels rotates in an opposite direction at the same rotational velocity. Forward movement is thus powered by the front wheels and rotating beams, while the rotational velocity of the rear wheels relative to the terrain is zero.
U.S. Pat. No. 4,932,491 describes a vehicle having auxiliary wheels that can be deployed to avoid overturning the vehicle when turning, traversing a slope, climbing an embankment or the like, and to right the vehicle when it is overturned.
Although the above-described devices represent advances over previous designs, wheeled platforms and devices such as those disclosed in the above-listed U.S. patents have notable limitations. They are typically inefficient, complex, cumbersome, heavy, and poorly suited to high-mobility operations on rough terrain or surfaces, such as traversing steep slopes, maneuvering around obstacles, and ascending or descending ramps or stairs.
Accordingly, there exists a need for wheeled platforms better suited to high-mobility, high-agility applications on rugged terrain and steep pitches. Ideally, such structures would be relatively robust, reliable, and conservative of battery or other energy sources, while providing enhanced abilities to traverse challenging terrain, and in some instances, to ascend or descend stairs and other obstacles. It is also desirable that such platforms be relatively compact, but scalable by selection of components and overall dimensions to adapt to various expected (and unexpected) terrain requirements.